My 1999 C-280 factory anti-theft is having premature alarmanation! Last week…for no apparent reason upon exiting my vehicle, closing the door, and setting the alarm with the remote...it immediately sounded. It continues to do this hence; I'm forced to keep my vehicle unlocked till I solve this challenge. In my efforts to correct, I discovered that the trunk lock cylinder was corroded. I removed it and had it rebuilt by a locksmith and just reinstalled…the condition still exists. I live in a cold climate, car has 85K miles and no prior alarm problems. I’m thinking sensor but would appreciate any tips on how to fix it!